Alex Rodriguez probably will earn more than $300 million if he leaves the New York Yankees and signs with a new team, Hall of Famer Reggie Jackson said.

“Yes, if I was a betting man,” Jackson said when asked if he thought the ex-Mariner might land a free-agent contract bigger than the record 10-year, $252 million one he signed with the Texas Rangers in 2000.

Now a special adviser to the Yankees, where he played from 1977 to 1981, Jackson said Rodriguez should consider his financial options while focusing on winning when he makes his decision whether to opt out of the final three years of his contract with New York.

The ex-player known as “Mr. October” for his feats in the World Series noted that Rodriguez hasn’t been on a World Series winner.

“I had no numbers like A-Rod had, but I’m recognized for championships,” Jackson said. “We’re not concerned about the numbers that Joe Montana put up, and we don’t know what Michael Jordan’s scoring average was, just that he was a champion.”

Rodriguez, 32, has an option to terminate the final three years and $81 million of his agreement.

Yankees general manager Brian Cashman reiterated on Wednesday the team’s stance that it will not negotiate with Rodriguez if he ends the current contract.

“I would like to see A-Rod chase greatness, and it’s here with the Yankees,” Jackson said. “It’s the trail of Ruth, and Gehrig and Mantle and players of that level.”